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Heavy artifacts problems after Lightroom export (Nikon Z7)

Forum|Forum|4 years ago
September 11, 2021
5 replies
910 views

Hello all,
I have a huge problem with my Nikon Z files in Lightroom. I am running the latest version of Lightroom 4.0 (Lightroom Classic 10.4). There are really bad artifacts in the sky (and snow) on the images after export. It looks like a mix of halos and chromatic aberrations and really nasty onion patterns. The exported photos are absolutely unusable. None of this is visible on the photo in Lightroom, not even the smallest trace at 100% magnification. First of all, the monitor is calibrated and it has nothing to do with that - the artifacts occur on the screen, but also on the iPhone. The problem exists exclusively with Nikon files, neither with Fuji, nor with Canon. Below are the settings:

Since Lightroom does not have profile corrections for Nikon Z (why not, really?), the internal camera and lens profile is applied.

Internal camera settings:

Lossless RAW Compression: ON
Color depth for Raw: 14-bit
Vignetting correction: Neutral
Color space: Adobe 1998
Diffraction compensation: On
Auto distortion correction: On

I am now posting a screenshot of the processed image in Lightroom and then of the exported file. Then also again the unprocessed file (again, the artifacts are already starting to show). The edited file is just un-creatured (tone curve S-shape) and a few minor adjustments....

Thanks for your help!

Windows

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Correct answer Jao vdL

The web output option in C1 defaults to scaling down the image heavily. This is why even at 2MB it still can look good. You'll see that if you zoom in on the export the image will be pixelated. Jpeg output quality is simply a function of compression level and pixel size of the export. In your expot settings you were not scaling down the image. What you should do is enable scaling, set a long edge size of 1800 pixels (for example) and enable output sharpening at medium screen level. You should be able to get a file that will look better than the C1 output at 2MB. You cannot actually export a full resolution image from a Z7 original (i.e,. 45 MP!) to a 2MB jpeg and expect it to look good. You will have to scale down the number of pixels considerably for that to work. The settings you showed (10 MB max file size without scaling) will always result in posterizing simply because of how the jpeg compression algorithm works. It is a lossy algorithm. There is no way around that and there is no magic sauce in any other program. They all use more or less the exact same code for jpeg compression and they will all look similar at that file size if you do NOT scale down the image and use similar quality settings. So, if you scale down to a more reasonable size (e.g. for web display you don't need more than 1000 to 2000 pixels on the long side) you will see the file size can be around 1 MB and still look good. Of course the file won't be suitable for gigantic prints as you scled down from 45 MP to around 2MP but it will be perfectly fine for display on the web.

With jpeg, best approach is to NOT use the limit file size option but simply dial in a quality. By forcing a file size you can force the algorithm to choose very low quality settings if you don't also scale the image. Typically anything above 85% will look great at any size. If you don't have gradient skies or other graduated colors, you can get away with less typically. Also scale down the image to what you need and use output sharpening if you scale down.

J

Jao vdL

Correct answer

Community Expert

The web output option in C1 defaults to scaling down the image heavily. This is why even at 2MB it still can look good. You'll see that if you zoom in on the export the image will be pixelated. Jpeg output quality is simply a function of compression level and pixel size of the export. In your expot settings you were not scaling down the image. What you should do is enable scaling, set a long edge size of 1800 pixels (for example) and enable output sharpening at medium screen level. You should be able to get a file that will look better than the C1 output at 2MB. You cannot actually export a full resolution image from a Z7 original (i.e,. 45 MP!) to a 2MB jpeg and expect it to look good. You will have to scale down the number of pixels considerably for that to work. The settings you showed (10 MB max file size without scaling) will always result in posterizing simply because of how the jpeg compression algorithm works. It is a lossy algorithm. There is no way around that and there is no magic sauce in any other program. They all use more or less the exact same code for jpeg compression and they will all look similar at that file size if you do NOT scale down the image and use similar quality settings. So, if you scale down to a more reasonable size (e.g. for web display you don't need more than 1000 to 2000 pixels on the long side) you will see the file size can be around 1 MB and still look good. Of course the file won't be suitable for gigantic prints as you scled down from 45 MP to around 2MP but it will be perfectly fine for display on the web.

With jpeg, best approach is to NOT use the limit file size option but simply dial in a quality. By forcing a file size you can force the algorithm to choose very low quality settings if you don't also scale the image. Typically anything above 85% will look great at any size. If you don't have gradient skies or other graduated colors, you can get away with less typically. Also scale down the image to what you need and use output sharpening if you scale down.

M

marcellf76730381Author

Participant

Hi buddy, first of all thanks for your objective answer 🙂 I found out that the problems "only" occur when the file is limited to less than 10 MB when outputting in lightroom. But who wants to flood his hard drive with 10 MB JPEGs..As soon as the file size is below that, the artifacts become immediately visible. A file output to 5 MB is unusable. for comparison I downloaded the C1 test version for Nikon. With the "web output" on 2 MB the image is razor sharp and there are no artifacts..It shows at the point again that C1 is the much better converter, but the workflow is for me a catastrophe -but I am a lazy retoucher 😉

J

Jao vdL

Community Expert

>Since Lightroom does not have profile corrections for Nikon Z (why not, really?), the internal camera and lens profile is applied.

It just uses the correction parameters Nikon provides in the raw files. Unfortunately for the Z7 (I have the same camera) you can't turn it off. This forced correction can cause bad artefacts in starry night pictures and I deeply dislike that Adobe does not allow you to turn it off but apparently that boat has sailed. On the newer Z cameras (Z7II etc.) they do allow you to turn it off meaning that this would be a trivial change to enable for 'older' mirrorless cameras but they are holding fast on this.

J

Jao vdL

Community Expert

The problem is very likely that you used the limit file size option while not resizing. This likely made Lightroom choose a low quality for the jpeg export. Try exporting at a quality higher than 85 or resizing the image to a much smaller size (so the algorithm won't have to choose such a low quality). These stair step artefacts are very typical for jpeg compression at low quality settings. Learn more about jpeg quality effects here: http://regex.info/blog/lightroom-goodies/jpeg-quality

M

marcellf76730381Author

Participant

Picture description (From top left to bottom right):

1) Edited file - viewed in Lightroom

2) Edited file magnification of the top left - viewed in Lightroom

3) Edited file with heavy artifacts - JPEG after Lightroom export

4) Edited file magnification of the snow at the bottom - JPEG after Lightroom export

5) Edited file magnification of the top left - JPEG after Lightroom export

6) Unedited raw file - JPEG after Lightroom export

7) Export settings

😎 Unedited raw file, magnification of the top left - JPEG after Lightroom export

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